<template>
    <div>
        <div>a:{{ a }} <button @click="a++">a+</button></div>
        <div>b:{{ b }} <button @click="b++">b+</button></div>
        <div>c:{{ c }} <button @click="c++">c+</button></div>
    </div>
</template>
<script lang='ts' setup>
import { ref,watch } from 'vue'
let a = ref<number>(10)
let b = ref<number>(20)
let c = ref<number>(30)
watch([a,c],(newval,oldval)=>{
    console.log('newval',newval,'oldval',oldval);   
})

</script>
<style lang='scss' scoped></style>